JOHANNESBURG (miningweekly.com) - Acid mine drainage (AMD) and, more specifically, a solution to AMD, have developed into a hot debate since the first decant of this toxic water became evident in 2002.

AMD has been described as one of the most serious and potentially enduring environmental problems for the mining industry and, if left unchecked, could result in long-term water-quality impacts that could well be the South African mining industry’s most harmful legacy.

Government is a significant stakeholder in the selection of an appropriate and economical solution to the problem; however, to date, it has yet to sign off on a suitable project. Expectations are that government should make a decision within the next couple of weeks.

One of the options being debated is the Western Utilities Corporation (WUC) project. WUC was commissioned by relevant mining companies in the affected areas to develop a holistic, integrated plan for the treatment of the AMD in the three geological structural basins in Gauteng.

The company developed a five-point plan that includes securing sufficient AMD to feed large-scale water treatment plants on an ongoing basis; the investigation and selection of suitable technology to treat AMD to produce drinking and industrial water, complying with all legal requirements; securing long-term, large-scale users for the drinking and industrial water produced; and raising funding for the project.

The project intends to implement the alkali-barium-calcium process developed by South Africa’s Council for Scientific and Industrial Research to treat AMD and produce drinking and industrial water.

Critical milestones for the pro- ject include the submission of its environmental-impact assessment to the Gauteng Department of Agriculture and Rural Development in October 2009 – the project is awaiting author-isation for this by the Department of Water Affairs by December 2009.

WUC MD Jaco Schoeman says that, while the estimated cost of implementing the WUC solution is more than R2-billion, mining companies associated with the Western, Eastern and Central basins of Gauteng have already committed substantial existing infrastructure worth more than R500-million to the project.

In addition, prefeasibility and bankable feasibility studies costing some R60-million have been funded by the Development Bank of Southern Africa (DBSA), with equity raised through Watermark Global, of which WUC is a wholly owned subsidiary, to be used for construction. Schoeman says that the project intends securing up to R1,5-billion of funding in equity through Watermark and in debt through commercial banks, the DBSA and the Industrial Development Corporation. Further operations and expansions will be funded through inter- nal cash flows and further debt and equity raisings.

The WUC plan envisages the start of plant construction in 2010, with generation of first product early in 2011.

Suboptimal Solution

However, water specialist Dr Anthony Turton says that the WUC deal will lock the country into a suboptimal solution. He notes that no process removes 100% of the impurities in AMD 100% of the time. “The WUC spin doctoring is presenting a ‘crisis’ with only one option.”

He suggests that the mine void be used for alternative strategic storage. “This will manage evaporative losses better and will also change the cost-to-benefit ratio of the AMD process, while still protecting the environment, but, more importantly, it will also prevent the human consumption of what is very bad water. It is imprudent to use anything but the best quality feedstock for potable water.”

Schoeman says that the claims that WUC’s product solution is suboptimal, and will result in the South African public consuming ‘very bad water’, are, simply, yet profoundly, scientifically flawed.

“WUC’s drinking water will be produced to comply with the standards of the South African National Accreditation Systems (Sanas) and the South African Bureau of Standards, and will thus be directly comparable with the drinking water currently bought by bulk consumers such as Rand Water.

He adds that, theoretically, the postulation that mine voids be used for strategic counter- evaporation storage is admirable. “However, its practicability, parti-cularly in the critically tight timeframes that the AMD situation dictates, is dubious, to say the least.

“The Western Basin is currently filled with water and decanting on surface, causing a number of concerns for downstream users, who are asking for immediate action. This impact will be repeated at four times the magnitude in Boksburg, Germiston and Johannesburg if there is not an operational solution in place within the next two years,” says Schoeman.

Turton agrees with Schoeman that the AMD must be treated, but not sold for drinking purposes. “I believe that is irresponsible and I will never support that. What should happen is that the treated AMD must be used as industrial process water only, and that will also relieve the stress on drinking water.

“However, this will not generate the revenues that WUC needs to meet its investors’ obligations and this is the only reason why WUC insists it must be sold for drinking purposes. This is our only point of disagreement.”

Turton points out that Schoeman never says that the water will be safe for human consumption. “He simply says that the water will meet Sanas quality standards. The reason for this is that WUC is solving a mine problem and not a national strategic storage problem. They are externalising the costs of remediation onto society. The only way this can be done is to make people fear the fact that the alternative will be a disaster, and to sell the water to the highest revenue generator, which is potable water in Gauteng,” he says.

Further, he comments that the law says that the polluter must pay. “This means that the mines must pay so they cannot use the excuse that the failure by the Minister to sign the offtake agreement will result in a disaster. This is brinkmanship. The mines caused the pollution, so the mines are legally obliged to pay for remediation. It is that simple. Sustainability is their problem and not the public’s.”

‘The polluter pays’ principle is laudable in theory and WUC agrees with this principle, says Schoeman. “To labour it practically, however, is to overlook the fact that most of the mining companies responsible for AMD no longer exist. The AMD issue has been around since mining started in 1886, over 120 years ago. To hold ‘the last men standing’ accountable is both a legally and an ethically flawed position. It also overlooks the fact that ‘the last men standing’ will go out of business one day and that their rehabilitation provisions, no matter how robust, will not last forever.”

Schoeman emphasises that the WUC proposal does not externalise the cost of remediation to society. “To fund capital requirements, WUC intends taking its proposal to the international investing community as an investment proposition and to lenders such as banks. WUC’s liabilities to these investors and lenders will be met from the revenues it generates, just like any other commercially sustainable business. Society can expect that it will pay no more for WUC’s product than it pays other providers of potable water, now and into the future.”

Working Together

Water engineering company Cwenga Technologies director Ed Hardwick welcomes any potential solution to the AMD problem. “The WUC plan could be part of the overall solution, but is not the only solution.

“We need to take the best of all available technologies and use them together, rather than having competing technologies claiming to be the whole solution.”
The ion-exchange technology that Cwenga has developed in conjunction with its partners is compatible with all other technologies, but it does not pretend to be the total solution to all the complex issues related to AMD, says Hardwick.

“Cwenga agrees completely that the mines need to take responsibility for their environmental liability and, in our exper- ience, the mines are doing so to the best of their ability. Part of the problem is an adversarial attitude sometimes [prevalent] between mines, regulators, utility suppliers and the media. We can solve the AMD problem, effectively, at a reasonable cost and reasonably quickly, by working together.”

The company is currently running pilot trials at a gold mine in the North West province to remove uranium from AMD and groundwater, using its ion- exchange technology.

Environmental & Remedial Technology Holdings (Earth) director Richard Doyle agrees with Hardwick, saying that AMD is a massive problem and that it is doubtful that a single company will be able to solve the problem.

“There are a number of technologies able to solve the problem; the issue is, as always, to decide on the right technology at the right economics.”

Doyle says that, even if the WUC plant goes ahead, it will meet less than 10% of the total need in South Africa during the first phase and less than 20% in the second phase, which means that government still needs to consider additional ways of solving the AMD problem.

“Anglo Coal is, arguably, the most advanced practitioner in the testing and application of technologies to treat AMD, and has moved from producing potable water to exploring completely effluent-free and sustainable solutions.

“Those providers that are able to offer sustainable solutions and are equipped with the ability to treat different effluent qualities are likely to find favour. Here Earth, which is a newer entrant than WUC, comes into its own. It has demonstrated capability at pilot scale and has the support of one of the largest engineering houses in the country,” says Doyle.

He reports that Earth has successfully treated AMD from three different coal AMD sources and two different gold AMD sources. “The ability to produce useful and saleable products from all effluent, with the exception of a small amount of solid material from backwashing the sand filters at the front end, makes this the only truly sustainable tech-nology on the market, at commercially competitive costs,” comments Doyle.

Earth is also in the process of showing that its ion-exchange technology can reprocess brines or liquors from reverse osmosis plants. “This will enable the company to not only offer effluent-free solutions, but also to clean up effluent streams from existing AMD plants.”

The company is in discussions with a number of large mining groups in the country in a number of different mining sectors regarding the implementation of its technology.

Doyle says that the ion-exchange technology has three major advantages over other technologies. Firstly, it extracts all the ‘dirty’ components of the polluted water effectively and produces ultraclean water. Secondly, the process can ‘sort’ the pollutants into their individual components (ions) and then reassemble them into different combinations, or with other chemicals, to produce useful and valuable materials that can be sold. Thirdly, it is possible to develop a residue-free system, sustainable in the long term after mine closure.

With all this taken into account, it stands clear that Government needs to implement a solution shortly, otherwise the toxic water will rise to surface and decant, which will contaminate groundwater, possibly cause sinkhole formations and destroy eco- systems.